CN113024153B

CN113024153B - Liquid cement synergist

Info

Publication number: CN113024153B
Application number: CN202110411547.0A
Authority: CN
Inventors: 陈礼平; 高全英; 陈骁斌
Original assignee: Hangzhou Lipin Technology Co ltd
Current assignee: Hangzhou Lipin Technology Co ltd
Priority date: 2021-04-16
Filing date: 2021-04-16
Publication date: 2022-05-17
Anticipated expiration: 2041-04-16
Also published as: CN113024153A

Abstract

The application relates to the field of concrete additives, in particular to a liquid cement synergist which comprises a polycarboxylic acid compound, ethylene-vinyl acetate emulsion powder, active micro powder, aromatic polycarboxylic acid, a cosolvent and water. In the application, through the compounding of the components, the beneficial effects of good glue reducing effect and concrete workability and strength can be realized.

Description

Liquid cement synergist

Technical Field

The application relates to the field of concrete additives, in particular to a liquid cement synergist.

Background

The cement synergist is an additive for reducing the cement consumption in the production process of concrete. In the production process of concrete, the cement can bond the aggregate components together through hydration reaction to form a gel system, and then the coarse aggregate and the fine aggregate are combined together, so that the concrete generates strength. However, since cement is not sufficiently hydrated during use and is present only as a filling component in a concrete structure, a large amount of cement is often added to form a sufficient gel structure in concrete, which also limits the strength of the entire concrete. The cement synergist is added to ensure that cement can react more fully in a concrete system, so that the using amount of the cement is reduced, and the strength of the concrete is improved.

The existing cement synergist mainly takes polycarboxylic acid compounds as a main component, and the polycarboxylic acid compounds can improve the dispersibility of cement, so that the cement has better dispersibility in a concrete system, thereby being easier to participate in reaction and reducing the formation of a cement filling system. However, in the above process, the reaction balance of cement is limited, and the formed gel structure has general strength and has a larger space for improvement.

Disclosure of Invention

In order to improve the strength of a concrete structure after cement is hydrated to form gel, the application provides a liquid cement synergist.

The application provides a liquid cement synergist specifically adopts the following technical scheme:

a liquid cement synergist comprises the following components in parts by mass:

in the technical scheme, the polycarboxylic acid compound and the ethylene-vinyl acetate latex powder are selected as the dispersion promoting system, the polycarboxylic acid compound is a high-efficiency surfactant, the dosage of cement and water can be reduced simultaneously, the cement dispersibility is improved well, the ethylene-vinyl acetate latex powder is generally used for preparing mortar and has certain film-forming and water-retaining properties, and in the application, the ethylene-vinyl acetate latex powder can form a film-shaped structure on the outer surface of partial aggregate in the processing process, so that the uniformity of the overall distribution is improved. The two are mixed together, and the aim is to maintain the fluidity and the uniformity of the concrete before setting so as to improve the dispersibility of the cement.

The purpose of the active micro powder is to catalyze the cement hydration reaction, so that a gel system can be formed quickly. The key point of the technical scheme is that the aromatic polycarboxylic acid has a multidirectional coupling effect, and the polybasic carboxyl can form a chelating system with calcium and aluminum in cement to form a latticed structure. Meanwhile, the aromatic polybasic acid has stronger chelating property, and can be well coupled together by adding the aromatic polybasic acid to cement which does not participate in hydration reaction, so that the strength of concrete is greatly improved. In addition, compared with aliphatic polybasic acid, the aromatic polybasic acid has stronger coupling capacity and stronger rigidity after forming a grid structure, thereby having stronger improvement effect on the strength of the formed concrete. The strong reactivity of the surface of the active fine powder can promote the reaction of the aromatic polycarboxylic acid, and the overall strength can be further improved by the polar force or the pi-bond interaction force. The purpose of the co-solvent is to improve the solubility of the aromatic polyacid in water, to facilitate the above reaction, and to improve the overall uniformity and fluidity.

In conclusion, in the application, the polycarboxylic acid compound and the ethylene-vinyl acetate latex powder are added to improve the dispersion performance of the cement particles, and meanwhile, the aromatic polycarboxylic acid is added to perform a secondary coupling reaction on the cement particles which do not participate in the hydration reaction to form a firmer cross-linked network structure, so that the using amount of the cement is reduced, and the strength of the concrete is improved.

Optionally, the aromatic polycarboxylic acid comprises two or more aromatic rings connected by single bonds, and all carboxyl groups are not located on the same aromatic ring.

In the above scheme, aromatic rings are connected through a single bond, and have certain rotation, so that coupling can be more easily performed, and reaction difficulty caused by excessive twisting force in a molecule can be avoided. When all carboxyl groups are not on the same aromatic ring, the aromatic polyacid molecules can be better coordinated with a plurality of calcium atoms, but not coordinated with the same atom to form a chelate, so that more complex cross-linking structures can be formed in the system, and the strength of the finally obtained concrete is higher.

Optionally, the aromatic ring is a benzene ring, and at least one amino group or imino group is bonded to the aromatic ring.

On one hand, the amino or imino has the effect of auxiliary coordination, and the strength of coordination chelation is improved, so that the strength of the formed cross-linked network is higher. Meanwhile, the pH value in the hydrogel system can be adjusted, so that the hydration reaction can be smoothly carried out.

Optionally, the polycarboxylic acid compound contains a silane functional group.

The polycarboxylic acid compound with the silane functional group is adopted, on one hand, the binding capacity between the polycarboxylic acid compound and cement particles can be increased, so that cement can be dispersed more uniformly, the workability of concrete is better influenced, and meanwhile, in the cement particles coated with the silane coupling agent, calcium ions and aluminum ions are coordinated with aromatic polycarboxylic acid to form a more stable network structure.

Optionally, the molecular weight of the polycarboxylic acid compound is 30000-100000.

The polycarboxylic acid compound with the molecular weight of 30000-100000 is selected, so that the coating effect and the lubricating effect on cement particles are good, and the influence on the reactivity of the aromatic polycarboxylic acid is small.

Optionally, the polycarboxylic acid compound is obtained by polymerizing a macromolecular ether monomer, unsaturated carboxylic acid and a silane functional monomer, wherein the mass ratio of the unsaturated carboxylic acid to the silane functional monomer is (5-8) to 1.

After the ratio of the unsaturated carboxylic acid to the silane functional monomer is controlled to be (8-10) to 1, the synergist has a better synergistic effect, the dosage of cement is further reduced, and the strength of concrete is improved.

Optionally, the unsaturated carboxylic acid is one of acrylic acid, maleic acid, methacrylic acid, and maleic anhydride, the silane functional monomer is a silane coupling agent, and the macroether monomer is polyoxyethylene alkylphenol ether.

In the technical scheme, the polyoxyethylene alkylphenol ether is selected as the macromolecular ether monomer, compared with polyoxyethylene aliphatic ether, the compound can form pi-pi stacking with aromatic polybasic acid, and further control certain influence and limitation on the molecular chain trends of the compound and the aromatic polybasic acid, so that a formed cross-linked structure is not easy to disperse and break in the process of hydration reaction, and the strength of the concrete after molding is further improved.

Optionally, the gypsum plaster also comprises 3-6 parts by mass of gypsum.

The content of calcium ions in a system can be adjusted by adding the gypsum, the crosslinking degree of the calcium ions and the aromatic polycarboxylic acid is further improved, the formed net structure is denser, meanwhile, the calcium ions in the gypsum are free calcium ions, a certain retarding effect can be achieved, a gap filling effect can be achieved in the hydration reaction process, the compactness of concrete is further improved, and the gaps in the concrete are reduced.

Optionally, the cosolvent is one of ethylene glycol, 1, 3-propylene glycol and glycerol.

In the technical scheme, the polyol is used as the cosolvent, can play a role in auxiliary lubrication, has small influence on the strength of the concrete and the progress of the hydration reaction, and can be fully dissolved so that the reaction can be smoothly carried out.

Optionally, the active micro powder is a composition of active silicon micro powder and ceramic powder, and the mass ratio of the active silicon micro powder to the ceramic powder is (3-4) to 1.

The active silica powder has good reaction activity, can promote the hydration reaction, reduces the using amount of cement, does not participate in the reaction, but has better filling performance, can fill the gap formed by the volume shrinkage of the concrete in the hydration reaction process, and further improves the performance of the concrete.

In summary, the present application includes at least one of the following advantages:

1. in the application, the polycarboxylic acid compound and the ethylene vinyl acetate rubber powder are adopted to improve the dispersibility of the cement, and the aromatic polycarboxylic acid is added to improve the crosslinking degree of a system, so that the cement consumption is reduced, and the mechanical strength of the concrete is improved.

2. In the further setting of this application, further added gypsum, provide free calcium ion through gypsum and fill the space in the gel system that hydration reaction formed in the concrete, further improved the intensity of concrete.

Detailed Description

The present application will be described in further detail with reference to examples.

In the following embodiments, the sources of some of the compounds are shown in table 1.

TABLE 1 partial ingredient Source Table

Composition (I)	Parameter(s)	Source
			Polyoxyethylene octylphenol ether	NPEO-7	Amresco
Silane coupling agent KH570		Group of traditional Chinese medicines
			Hydrogen peroxide solution	The mass fraction is 20 percent	Bo ao zhong cheng chemical industry
Lauric acid polyoxyethylene ether	PEG200DL	Amresco
			Ethylene-vinyl acetate emulsion powder	LDM 1646P	Wake Corp Ltd
Active silicon micro powder	400 mesh	Liyunnang vast crystal silicon material
			Ceramic powder	200 mesh	China porcelain material
Coarse aggregate	5-30 mm limestone	Linan cool and refreshing peak
			Fine aggregate	5-10 mm limestone	Linan cool and refreshing peak
Sand	Machine-made sand	Xixin sandstone
			Ordinary Portland 325 cement		Three lion Cement plant

Preparation examples 1 to 12 are methods for synthesizing polycarboxylic acid compounds.

Preparation example 1, polycarboxylic acid-based compound, synthesized by aqueous solution radical polymerization method, was as follows: adding 20mM octyl phenol polyoxyethylene ether into an aqueous solution, heating to 80 ℃, fully and uniformly mixing, adding ascorbic acid according to the concentration of 0.2mM, adding hydrogen peroxide according to the concentration of 0.5mM, then dropwise adding a mixed solution of methacrylic acid and a silane coupling agent KH570, wherein the dropwise adding mass of the methacrylic acid is 0.1 time of that of the octyl phenol polyoxyethylene ether, the mass ratio of the silane coupling agent to the methacrylic acid is 1:5, the dropwise adding time is 2 hours, after the dropwise adding is finished, carrying out heat preservation reaction for 12 hours, then carrying out reduced pressure distillation at 80 ℃, removing the solvent, and cooling to room temperature.

Preparation example 2, a polycarboxylic acid-based compound was different from preparation example 1 in that the ratio of the amount of the silane coupling agent KH570 to the amount of methacrylic acid was 1: 8.

Preparation example 3, a polycarboxylic acid-based compound was different from preparation example 1 in that the ratio of the amount of the silane coupling agent KH570 to the amount of methacrylic acid was 1: 12.

Preparation example 4, a polycarboxylic acid-based compound was different from preparation example 1 in that the ratio of the amount of the silane coupling agent KH570 to the amount of methacrylic acid was 1: 3.

Preparation example 5 polycarboxylic acid-based compound, which is different from preparation example 1 in that methacrylic acid is replaced with acrylic acid in an equal amount.

Preparation example 6, polycarboxylic acid-based compound, was different from preparation example 1 in that methacrylic acid was replaced with maleic acid in an equivalent amount.

Preparation example 7, polycarboxylic acid-based compound, differs from preparation example 1 in that methacrylic acid is replaced with maleic anhydride in an equivalent amount.

Preparation example 8, polycarboxylic acid-based compound, prepared by the following method:

preparing 10mM lauric acid polyoxyethylene ether, heating to 50 ℃, uniformly stirring, adding thioglycolic acid serving as an initiator according to the concentration of 0.1mM, adding ascorbic acid according to the concentration of 0.5mM, adding hydrogen peroxide according to the concentration of 0.5mM, dropwise adding the acrylic acid and KH570 mixed solution within 10min, continuously reacting for 5h while keeping the temperature after dropwise adding, distilling at 80 ℃ under reduced pressure, removing the solvent, and cooling to room temperature.

Preparation examples 9 to 12, the polycarboxylic acid compounds are different from the preparation example 1 in that the polycarboxylic acid compounds with different molecular weight ranges are obtained by adjusting the concentration and the reaction time of the octylphenol polyoxyethylene ether and adjusting the concentrations of the initiator, the oxidant and the reducing agent according to the same proportion of the change times of the macromolecular ether monomers. In preparation examples 1 to 12, the specific conditions of the polyether monomer added, the reaction time under temperature, and the molecular weight of the finally obtained polycarboxylic acid compound in the preparation of the polycarboxylic acid compound are shown in Table 2.

TABLE 2 molecular weight control of polycarboxylic acid Compounds in preparation examples 1 to 12

In the above preparation examples, the molecular weight was measured by gel chromatography using an aqueous solution of sodium nitrate having a mass concentration of 0.1% as a mobile phase, and the flow rate was controlled at 35 ℃ to be 1mL/min, and the amount of sample was 20. mu.L, and a base line was made with respect to the molecular weight using polystyrene as a standard substance.

On the basis of the above preparation examples, the following examples were set up.

Example 1 a liquid cement synergist was prepared by adding a polycarboxylic acid compound, ethylene-vinyl acetate rubber powder, active fine powder, an aromatic polycarboxylic acid, and a cosolvent to water, and stirring the mixture uniformly.

Wherein the aromatic polycarboxylic acid is 4, 4-biphenyldicarboxylate, and the polycarboxylic acid compound is the polycarboxylic acid compound prepared in preparation example 1. The cosolvent is ethylene glycol. Specific composition ratios are shown in table 3, for example.

Examples 2 to 3 are different from example 1 in that the proportions of the polycarboxylic acid compound, ethylene-vinyl acetate rubber powder, active fine powder, aromatic polycarboxylic acid, cosolvent and water are shown in table 3.

In addition, the following comparative examples 1 to 4 were provided in the above examples, and the differences from example 1 were that the ethylene-vinyl acetate rubber powder, the active fine powder, the aromatic polycarboxylic acid, and the cosolvent were not included in any of the components, and the specific ratios of the substances are shown in table 3.

TABLE 3 Components in examples 1 to 3 and comparative examples 1 to 4 (parts by mass)

Examples 6 to 16 are different from example 4 in that the polycarboxylic acid-based compounds of preparation examples 2 to 12 were used as the polycarboxylic acid-based compounds, respectively.

Example 17 is a liquid cement synergist different from example 4 in that the polycarboxylic acid-based compound is selected from SPC-100 standard type polycarboxylic acid high performance water reducing agent purchased from the Koron group.

Examples 18 to 22 are different from example 4 in that aromatic polybasic acids are specifically selected as shown in Table 4.

TABLE 4 molecular formula of aromatic polycarboxylic acid selected from examples 1 to 22

Example 23, a liquid cement synergist, differs from example 18 in that it further includes 3 parts by mass of gypsum.

Example 24, a liquid cement synergist, different from example 18, further comprising 6 parts by mass of gypsum.

Example 25, a liquid cement synergist, differs from example 18 in that the co-solvent is 1, 3-propanediol.

Example 26, a liquid cement synergist, differs from example 18 in that the co-solvent is glycerol.

In addition, for the aromatic polycarboxylic acid, the following comparative examples were set:

comparative example 5, a liquid cement synergist, differs from example 17 in that an aromatic polybasic acid is replaced with succinic acid in an equivalent amount.

Comparative example 6, a liquid cement synergist, differs from example 17 in the amount of 4, 4-diaminobiphenyl used.

For the above examples and comparative examples, the patterns were prepared and measured in the following manner.

The formula 1 is prepared by mixing liquid cement synergists in examples 1 to 25 and comparative examples 1 to 6 according to a mass ratio of 1200 parts of coarse aggregate, 650 parts of fine aggregate, 120 parts of water and 1080 parts of sand, wherein the mass parts of the liquid cement synergists are 300 parts of ordinary Portland cement, and the specific gravity of the total mass is 3 per mill, stirring for 200s, casting into cubic blocks of 30cm x 30cm, standing for 24h after casting is completed, and then demolding and maintaining.

And 2, according to the mass ratio of 1230 parts of coarse aggregate, 650 parts of fine aggregate, 100 parts of water and 1110 parts of sand, and 250 parts of ordinary Portland 325 cement by mass, according to the specific gravity of 3 per mill of the total mass, the liquid cement synergist in the examples 1-25 and the comparative examples 1-6 is added, the mixture is stirred for 200s, and cast into cubic blocks of 30cm x 30cm, the cubic blocks are stood for 24h after casting is finished, and then the casting is carried out for maintenance.

And the style 3 is that according to the mass ratio of 1260 parts of coarse aggregate, 650 parts of fine aggregate, 80 parts of water and 1140 parts of sand, 200 parts of ordinary Portland 325 cement is mixed with the liquid cement synergist in the examples 1-25 and the comparative examples 1-6 according to the specific gravity of 3 per mill of the total mass, the mixture is stirred for 200s, and cast into cubic blocks of 30cm multiplied by 30cm, and the cubic blocks are stood for 24h after casting is finished, and then the mixture is demoulded and maintained.

For the three types, the slump of the concrete mixture is measured 30min after the concrete is mixed, the cohesiveness of the concrete mixture is judged in a knocking mode after the concrete is mixed, if a cone formed by the slump sinks gradually, the cohesiveness is good, and if the cracking and collapsing phenomena occur, the cohesiveness is poor. Meanwhile, the compressive strength was maintained for 28 days.

The measurement results of examples 1 to 5 and comparative examples 1 to 4 are shown in Table 5.

TABLE 5, EXAMPLES 1-5 AND COMPARATIVE EXAMPLES 1-4 Experimental results contrasts

According to the experimental data, the liquid cement synergist used in the application can effectively improve the cohesion and the fluidity of a concrete mixture in the process of preparing concrete, and the strength of the concrete after 28-day maintenance is obviously improved while the fluidity is improved. In the application, with the reduction of the amount of the used cement, the slump loss is small, and the strength is improved by a small amount, so that the fact that the liquid cement synergist in the application is used for the second time is proved to effectively reduce the using amount of the cement, and the effect of reducing the cement and enhancing the cement is achieved.

In comparative example 1, the absence of the ethylene-vinyl acetate latex had a greater effect on the fluidity of the concrete. In the application, the crosslinking capability of the liquid cement synergist is stronger, so that when ethylene-vinyl acetate latex powder is lacked, the overall fluidity is greatly reduced, the distribution is uneven, the number of gaps in a system is larger, and the strength of concrete is further reduced. The lack of active micro powder in comparative example 2 has adverse effect on the progress of hydration reaction, which in turn causes the strength of concrete to decrease. Comparative examples 3 and 4 lack aromatic polycarboxylic acid and cosolvent, respectively, and in the case of lack of cosolvent, the aromatic polycarboxylic acid has poor dispersibility in the system, the crosslinking effect is difficult to realize, and the strength of the concrete is also greatly influenced.

In example 4 and example 5, compared with example 1, the ceramic powder is additionally added, and on one hand, the ceramic powder can play a lubricating role in a system, and has the effects of filling gaps and improving strength.

The measurement results of examples 6 to 16 are shown in Table 6

TABLE 6 comparison of experimental results of examples 5 to 15

From the above experimental data, it can be seen that the aromatic polycarboxylic acid compound has certain advantages in improving the strength of concrete compared to the aliphatic polycarboxylic acid compound in the selection of the polycarboxylic acid compound. In examples 6 to 9, the amount of the silane coupling agent was adjusted, and when the silane component was too large, the strength of the concrete was adversely affected, and the applicant considered that the reason for this was probably that silane itself competed with the polyvalent aromatic carboxylic acid by intermolecular force, and further that a part of weaker force was substituted for stronger force, and the cohesive force of the concrete was rather weakened.

In example 17, the polycarboxylic acid-based compound containing no organosilicon component was used, and the overall fluidity was inferior to that of example 6, and the slump-decreasing tendency was more remarkable and the cohesion was weaker as the amount of cement used was decreased.

The measurement results of examples 18 to 22 are shown in Table 7.

Table 7, examples 18 to 22 and comparative examples 5 to 6 show comparative results

From the above experimental data, it can be seen that in the present application, the aromatic polycarboxylic acid has better coordination ability and bonding strength than the aliphatic polycarboxylic acid (succinic acid) in comparative example 5 and the aromatic polyamine (4, 4-diaminobiphenyl) in comparative example 6, and has an adverse effect on the cohesion of the concrete mix and the strength after the concrete is molded.

In examples 19 and 22, aromatic polycarboxylic acids having amino groups or imino groups are used, and the aromatic polycarboxylic acids have better coordination ability and stronger binding force, and can also adjust the dispersion and coating properties of polycarboxylic acid compounds on cement particles, so that the concrete mixture has better fluidity and stronger cohesive force.

The measurement results of examples 23 to 26 are shown in Table 8.

TABLE 8 comparison of experimental results of examples 23 to 26

According to the experimental data, after the gypsum is additionally added, a more detailed grid structure can be formed through calcium ions in the gypsum, and the strength of the concrete after forming is further improved.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims

1. The liquid cement synergist is characterized by comprising the following components in parts by mass:

45-60 parts of polycarboxylic acid compounds;

20-30 parts of ethylene-vinyl acetate latex powder;

10-15 parts of active micro powder;

6-10 parts of aromatic polycarboxylic acid;

3-15 parts of a cosolvent;

70-100 parts of water;

the aromatic polycarboxylic acid comprises two or more aromatic rings connected by single bonds, and all carboxyl groups are not positioned on the same aromatic ring; the aromatic rings are benzene rings, the number of the benzene rings is 2-3, and the aromatic rings are linked with at least one amino group or imino group;

the molecular weight of the polycarboxylic acid compound is 30000-100000; the polycarboxylic acid compound is obtained by polymerizing a macromolecular ether monomer, unsaturated carboxylic acid and a silane functional monomer, wherein the mass ratio of the unsaturated carboxylic acid to the silane functional monomer is (5-8) to 1; the polycarboxylic acid compound contains a silane functional group;

the unsaturated carboxylic acid is one of acrylic acid, maleic acid, methacrylic acid and maleic anhydride, the silane functional monomer is a silane coupling agent, and the macromolecular ether monomer is polyoxyethylene alkylphenol ether;

the cosolvent is one of ethylene glycol, 1, 3-propylene glycol and glycerol.

2. The liquid cement synergist according to claim 1, further comprising 3-6 parts by mass of gypsum.

3. The liquid cement synergist according to claim 1, wherein the active fine powder is a composition of active fine silica powder and ceramic powder, and the mass ratio of the active fine silica powder to the ceramic powder is (3-4) to 1.